1. Field of the Invention
The present invention relates to a hydraulic control apparatus of a continuously variable transmission that is equipped in a hybrid vehicle, particularly a technology of efficiently generating hydraulic pressure required for a hydraulic control apparatus according to the traveling state of a vehicle.
2. Description of Related Art
FIG. 1 shows an example of a hydraulic control apparatus of a continuously variable transmission of a hybrid vehicle, in which hydraulic pressure supplied from an oil pump 500 is supplied toward a driving pulley 504 and a driven pulley 506 after being adjusted at predetermined pressure by a line regulator valve 502, the hydraulic pressure supplied toward driving pulley 504 is adjusted by a transmission gear ratio control valve 508 and then supplied to driving pulley 504, and the hydraulic pressure supplied toward driven pulley 506 is adjusted by a secondary valve 510 and then supplied to driven pulley 506.
The hydraulic pressure adjusted by line regulator valve 502 is also supplied to a second regulator valve 512, such that second regulator valve 512 adjusts hydraulic pressure that is supplied to a starting clutch control solenoid valve 514, a limp home valve 516, and a solenoid feed valve 518.
Starting clutch control solenoid valve 514 controls and supplies operational pressure for a reverse brake 520 and a forward clutch 522, solenoid feed valve 518 supplies the adjusted hydraulic pressure to a transmission gear ratio control solenoid valve 524, a secondary control solenoid valve 526, a line regulator solenoid valve 528, and a clutch lubrication control solenoid valve 530 to control transmission gear ratio control valve 508, a secondary valve 510, line regulator valve 502, and a lubrication control valve 532, respectively.
The other parts have configurations and functions that are not substantially different from those of hydraulic control apparatuses of continuously variable transmission.
The pressure supplied toward driving pulley 504 and driven pulley 506 from line regulator valve 502 is referred to as ‘pulley pressure’ and the pressure supplied to transmission gear ratio control solenoid valve 524, secondary control solenoid valve 526, line regulator solenoid valve 528, and clutch lubrication control solenoid valve 530 from solenoid feed valve 518 is referred to as ‘solenoid valve supply pressure’ herein.
When a vehicle stops in a D-range, other pressure does not substantially need to be supplied than the pulley pressure and the solenoid valve supply pressure required for quick operation when restarting the vehicle; however, existing structures of hydraulic control apparatuses cannot help supplying hydraulic pressure to unnecessary parts, such as the hydraulic pressure supplied toward forward clutch 522, which is inefficient.
That is, since hydraulic pressure is supplied to unnecessary parts when a vehicle stops in the D-range, energy is unnecessarily consumed and the efficiency of the continuously variable transmission is decreased.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.